AROIDEAE 493 



protogynous, but the stigmas are still receptive when the anthers dehisce, so that 

 autogamy is possible by fall of pollen. The insects attracted reach the trap either by 

 creeping along the projecting spadix or along the inner surface of the spathe. 



As a rule they are unwillingly detained there for some time, because they cannot 

 find the opening again, this being, as already described, overhung and shadowed by 

 the dark-coloured roof In endeavouring to reach the open air once more, they 

 always fly against the ten bright streaks on the spathe, through which the light 

 shines, and after many attempts usually only regain their freedom by chance, when, 

 wearied out, they begin to creep slowly to the top of the spadix. This barrier is so 

 effective that the plant may be carried about for some time without the escape of 

 a single insect from the trap, though if it is cut open they fly quickly away through 

 the slit. 



When pollination has been effected, the projecting part of the spadix shrivels 

 up, while the arched lobe of the spathe folds down and completely closes the entrance. 

 The offensive odour disappears at the same time, the spathe assumes an inconspicuous 

 pale-reddish colour, and finally falls off, together with the upper part of the spadix. 



Visitors. — Knuth (Capri) observed minute flies and midges, small ants, and an 

 earwig (Forficula decipiens Gene). 



2915. A. proboscideum Savi. — Arcangeli (Nuovo Giorn. bot. ital., Firenze, 

 xiii, 1895) states that this species is pollinated chiefly by fungus-midges (Myceto- 

 philidae). The upper part of the spadix serves partly to prevent the escape of 

 insects, and also partly, no doubt, as nourishment for them later. 



941. Dracunculus Adans. 



2916. D. vulgaris Schott (= Arum Dracunculus L.). — Delpino ('Ult. oss.,' 

 p. 2380) states that the flowers of this South European species are visited and 

 pollinated by flesh-flies. 



In Italy, however, Arcangeli (Nuovo Giorn. bot. ital., Firenze, xv, 1883) observed 

 carrion-beetles as the chief visitors ; in five inflorescences there were 463 beetles, 377 

 of them belonging to the species Saprinus nitidulus F. ■ he therefore describes the 

 plant as ' necrocoleopterophilous.' As in Arum italicum Mill., four stages of anthesis 

 may be distinguished : — 



(i) The spathe opens, the anthers being closed ; the stigmas are receptive and 

 are pollinated by beetles, which hasten, covered with pollen, to the flowers, attracted 

 by the smell of carrion. 



(2) The stigmas fade ; the anthers still remaining closed. 



(3) The anthers dehisce at the beginning of the second day ; the carrion-beetle 

 visitors dust themselves again with pollen. 



(4) The lower part of the spadix, hitherto smooth as a mirror, becomes wrinkled, 

 so that the carrion-beedes can climb up on it, reach the open air, and then pollinate 

 other flowers. 



Delpino and Mattel (Malpighia, Genova, iii, 1889-90, p. 38) assert that flies 

 (Calliphora vomitoria L., Sarcophaga carnaria Z., Lucilia sp. and so forth) may 

 actually be considered pollinators, so that the plant is sapromyophilous. They also 

 state that only flies are found in the traps of plants growing sporadically in woods. 



